Notes on 'Expert Oracle' - No.13.2: partition - partition mechanism

Q: What area by then? A: four kinds of programs 1. By numerical interval points. Such as [1-100] let A,, [101-200] put B, 2. By enumeration values of the discrete values of zoning, as in [Jiangxi, Fujian] let A,, [Beijing, Zhejiang] let B,. This is called "list partition" 3. Directly by the hash value of partition. This is fine to say. 4. Combined use of several regional mechanisms for more than several partitions, and then in the large partition into smaller partitions.

Q: Data does not migrate between partitions, right? A: will. 1. Such as the original records have a value of 1, on the A zone; now its value becomes 105, you must move the B zone. 2. This "moving line" is expensive. If you choose the extension mechanism leading to this kind of thing often happens that the District failed

1. To improve the system reliability (HA): do not put all your eggs in one basket a. A bad area, but the data partition B can still be inquiries into b. A bad partition, and restore the partition of the time table than the entire restoration was much

Q: What area by then? A: four kinds of programs 1. By numerical interval points. Such as [1-100] let A,, [101-200] put B, 2. By enumeration values of the discrete values of zoning, as in [Jiangxi, Fujian] let A,, [Beijing, Zhejiang] let B,. This is c

1. B * tree - an index of the most common 2. BitMap Index - mainly for a high degree of duplication of data, not for OLTP system 3. BitMap Join Index - table set up in the field for the index of another table 4. Function-based Index - can be the name

1. Structure a. similar to the binary tree b. a high degree of balance: all leaf nodes have the same level in the tree c. In general height is 2 or 3 (need 2 to 3 times I / O) 2.When B *? a. If the query with the index returned only a few rows, you c

1.B * null value of the index will not index the entire entry so select * from T where x is null will not use the index (if the index built on the x field) However, if the following two conditions, the index will be used a. index built in (x, y) on b

1. Note that character set, that NLS 2.char/nchar simply do not have access i. It will fill the vacant space through space, causing a waste of space ii. It also led to select ... where column_five_char = 'ABC' not hit record, because the database is

1. Generally use "Number" This type of 2. Database how to deal with the definition of precision than the input data? a. Rounding: too many decimal places, but the nearest whole number not exceeding, was rounded and decimal places to insert the d

1. Query, try to avoid the type in the date field to use the function a. make the field on which the index is invalid. Bad example: select ... where to_char (birthday) = '2010-1-1 ' Good: select ... where birthday = to_date ('2010-1-1 ') b. If the no

With the passage of time, data in the database table increases, the server has been overwhelmed, in order to solve this problem, a data partition of the software concept, called sharding. Here is the related idea of introducing the software. 1.Shardi

[Overview] [Partition table partition table and not during the test] [Partition Command Detailed] [Overview] 5.1 Since the beginning of the partition (Partition) with the support of 6.0 should be relatively stable = Horizontal partition (divided by r

MySQL partition (Partition) catalog function tests 2008-07-06 20:02 [Overview] [Partition table partition table and not during the test] [Partition Command Detailed] [Overview] 5.1 Since the beginning of the partition (Partition) with support from 6.

A few years ago, I wrote an article entitled "The Foundation of Excellent Performance" article (and still can http://www.tdan.com/i016fe03.htm see), I is the impact of database-driven SQL statement The first element of the system performance poi

For RANGE and LIST partitions, some examples from the Internet learned, can be specified for each partition corresponding database server, as follows: drop database if exists myspider; create database myspider; use myspider; Create table tbl_b ( col_